In many types of conventional wrapping apparatus for forming an elastic corespun yarn, and in some two-for-one twisting apparatus, a hollow rotating spindle carries a supply package of nylon or other nonelastic covering yarn. An elastic core yarn such as spandex is passed through the center of the hollow spindle. The nylon covering yarn is unwound from the rotating supply package and is wrapped around the elastic core yarn to form an elastic corespun yarn. The uninterrupted length of elastic corespun yarn formed by this apparatus is limited by the size of the covering yarn supply package which can be carried by the rotating spindle. Because the covering yarn is used at a much faster rate than the core yarn, the winding apparatus must frequently be stopped to replenish the covering yarn supply package.
It has been proposed to provide a longer run of elastic corespun yarn by providing a wrapping apparatus where the covering yarn is drawn from a stationary yarn supply package into surrounding, ballooning relationship with a package of elastic core yarn carried by a fixed spindle. The elastic core yarn is metered from the package and the covering yarn is wound in wrapping engagement with the drawn core yarn.
For example, in U.S. Pat. Nos. 2,737,773 and 4,309,867 to Clarkson and Ichikawa, respectively, the elastic core yarn is metered from a stationary supply package carried by a spindle. The elastic core yarn then is wrapped by the covering yarn. In U.S. Pat. No. 4,509,320 to Maeda, a core yarn package of elastic yarn is carried by a driven spindle while the drawn elastic core yarn is wrapped by the covering yarn. A tension device provides the proper amount of tension to the elastic core yarn during wrapping.
The aforementioned apparatus provide for the production of larger units of corespun yarn with the attendant fewer winding stops necessary for replenishing a yarn supply package of the winding yarn. These apparatus, however, mandate operation at a decreased winding speed. Operation of the apparatus at higher spindle speeds increases the centrifugal force of the covering yarn causing the covering yarn to break. Operation of this type of apparatus at high spindle speeds is also limited because of the weight of the elastic core yarn unwinding mechanism.